Sprint TOS change, Can my Contract be Voided?

I have Sprint cell phone service and have been waiting for my contract to be up in order to possibly change my service over to ting.com.  One interesting bit of legalese is that if Sprint materially changes their Terms of Service, you are allowed to get out of your contract without being charged an Early Termination Fee.

Well, they changed their TOS of July 1 and I noticed they added this bit:

Call time for a single call may be subject to a maximum duration and may be automatically terminated if the maximum duration is exceeded. Rates that vary based on the time of access will be determined based on the location of the network equipment providing service and not the location of your Device or your Device's area code (if applicable).

By adding this, they are allowing themselves to basically say a call that was an hour and spanned over a time period where rates are different (nights vs. days), can be split up over the two different time periods.  I would say, changing how my rates are possibly calculated is a material change and should be subject to allowing my to get out of my TOS.  What do you think?